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PubMedDate not supplied

Using a computer color-matching system in color reproduction of porcelain restorations. Part 2: Color reproduction of stratiform-layered porcelain samples.

Computer color matching is an excellent method for reproducing certain colors of various objects using a spectrophotometer and a computer. In this study the authors attempted to reproduce the color of layered porcelain samples according to the computer color-matching formulation, wherein a computer color-matched sample is made and compared with the target sample. The color differences between the computer color-matched samples (opaque/dentin and opaque/dentin/enamel) and the target samples approximated 1.0, and the samples were indistinguishable by visual observation. The spectral reflectance curves were also very similar.

Computer-Aided Design↗
PubMed2001

Venous neointimal hyperplasia in polytetrafluoroethylene dialysis grafts.

BACKGROUND: Vascular access dysfunction is the most important cause of morbidity and hospitalization in the hemodialysis population in the United States at a cost of $1 billion per annum. Venous neointimal hyperplasia (VNH) characterized by stenosis and subsequent thrombosis accounts for the overwhelming majority of pathology resulting in polytetrafluoroethylene (PTFE) dialysis graft failure. Despite the magnitude of the problem and the enormity of the cost ($1 billion), there are currently no effective therapies for the prevention or treatment of venous neointimal hyperplasia in PTFE dialysis grafts. METHODS: Tissue samples were collected from the graft-vein anastomosis of stenotic PTFE grafts during surgical revision. Specimens were graded using standard light microscopy and immunohistochemistry for the magnitude of neointimal hyperplasia and for the expression of specific cell types, cytokines, and matrix proteins. RESULTS: VNH was characterized by the (1) presence of smooth muscle cells/myofibroblasts, (2) accumulation of extracellular matrix components, (3) angiogenesis within the neointima and adventitia, and (4) presence of an active macrophage cell layer lining the PTFE graft material. Platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) were expressed by smooth muscle cells/myofibroblasts within the venous neointima, by macrophages lining both sides of the PTFE graft, and by vessels within the neointima and adventitia. CONCLUSIONS: Our results suggest that macrophages, specific cytokines (bFGF, PDGF, and VEGF), and angiogenesis within the neointima and adventitia are likely to contribute to the pathogenesis of VNH in PTFE dialysis grafts. Interventions aimed at these specific mediators and processes may be successful in reducing the very significant human and economic costs of vascular access dysfunction.

Actins↗
PubMed1994

Form and color reproduction for composite resin reconstruction of anterior teeth.

To obtain esthetic results with composite resin restorations, it is necessary to consider the following elements: the structure of composite resin; tint modifiers; opaquers; generic form; and surface texture. This article discusses these elements and presents clinical examples of techniques for achieving esthetic composite resin restorations.

Composite Resins↗
PubMed1994

[Docu-Rec: the recording of tooth-colored restorations with a computer-assisted documentation system].

A new computerized documentation system for tooth-colored restorations was established in a clinical setting of the University of Zurich School of Dentistry and evaluated during one year. Workstations (Apple) at the chairside being linked in a computer-net (Ethernet) were used for data acquisition. A newly developed software ("Docu-Rec", Zeller 1994) offered predefined and logically connected clinical and dental material parameters to the user allowing a rapid data entry. From February 1993 to January 1994, 14 dentists recorded a total of 598 tooth-colored restorations (491 Cerec inlays/onlays, 26 laboratory-fabricated inlays, 81 anterior composite resin restorations) by entering 56,810 parameters into the system. The average acquisition time for one restoration was 2 minutes. The system proved to be user-friendly and practical.

Adult↗
PubMed2004

Effect of different high-palladium metal-ceramic alloys on the color of opaque and dentin porcelain.

STATEMENT OF PROBLEM: The color of dental porcelain depends on the type of metal substrate. Little research has been done to document the effects of different types of high-palladium alloys on the color of dental porcelain. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different high-palladium alloys on the resulting color of dentin porcelain, as well as on that of opaque porcelain after simulated dentin and glazing firing cycles. MATERIAL AND METHODS: Three Pd-Cu-Ga alloys, Spartan Plus (S), Liberty (B), and Freedom Plus (F), and 5 Pd-Ga alloys, Legacy (L), IS 85 (I), Protocol (P), Legacy XT (X), and Jelenko No.1 (N), were examined. A Pd-Ag alloy, Super Star (T), was included for comparison to the high-palladium alloys, and the Au-Pd alloy, Olympia (O), served as the control. Six cast discs (16 x 1 mm) were prepared from each of the alloys. Shade B1 opaque porcelain (Vita-Omega) was applied at a final thickness of 0.1 mm. After 2 opaque porcelain firing cycles, the surfaces were airborne-particle abraded, and the specimens were divided into 2 groups. In the first group, 0.9 mm of B1 dentin porcelain was applied. The other group of specimens with only opaque porcelain underwent the same dentin porcelain and glazing firing cycles. Color differences (DeltaE) were determined with a colorimeter between the control and each experimental group, after the second opaque porcelain, second dentin porcelain, and glazing firing cycles. One-way analysis of variance and Dunnett's multiple range test were performed on the DeltaE data (alpha=.05). RESULTS: After the application of dentin porcelain, the 3 Pd-Cu-Ga alloys showed significantly different (P<.05) DeltaE values (S=2.3 +/- 0.5, B=1.4 +/- 0.3, and F=1.3 +/- 0.7) than the control group. After the glazing cycle of this group, the 3 Pd-Cu-Ga alloys and the Pd-Ag alloy exhibited significantly different (P<.05) DeltaE values (S=2.8 +/- 0.8, B=2.2 +/- 0.3, F=1.9 +/- 1.0, and T=1.4 +/- 0.5) than the control group. After the simulated dentin porcelain firing cycles, the specimens with only opaque porcelain exhibited significantly different (P<.05) DeltaE values (S=5.2 +/- 1.4, B=5.4 +/- 0.6, and F=3.9 +/- 0.2) than the control group. The color difference between the 3 Pd-Cu-Ga alloys with only opaque porcelain and the control group increased more after the simulated glazing cycle (S=6.6 +/- 1.5, B=6.3 +/- 0.5, and F=4.6 +/- 0.1). The observed color differences between the Pd-Ga alloys and the control group were not statistically significant at any point. CONCLUSIONS: The Pd-Cu-Ga alloys with only opaque porcelain, after the simulated dentin porcelain and glazing firing cycles, exhibited clinically unacceptable color differences. The application of dentin porcelain to the Pd-Cu-Ga alloys resulted in clinically acceptable color differences. The application of dentin porcelain to the Pd-Ag alloy, after the glazing firing cycle, resulted in clinically acceptable color differences (approximately 2.8 to 3.7 DeltaE CIELAB units). The Pd-Ag alloy specimens with only opaque porcelain did not exhibit significant color differences from the control group, whereas significant color differences from the control group after the dentin porcelain and glazing firing cycles were still clinically acceptable.

Analysis of Variance↗
PubMed1998

An innovative direct technique for resin composite veneers for teeth with color alterations.

An alternative technique for fabricating resin composite veneers for teeth with color alterations is presented. The technique is based on research carried out with a silica derivative (coesite). The veneer is applied directly to the mouth. The objective of the technique is to provide greater translucence to the teeth, resulting in a better imitation of the natural appearance.

Composite Resins↗
PubMedDate not supplied

The impact of angiodynography on infrainguinal bypass graft surveillance.

We have followed 64 lower extremity in situ grafts and 56 selected vein or prosthetic grafts with serial angiodynography since 1988 (Quantum Color-flow Duplex) and ankle/brachial indices (ABI). Each graft can be scanned in 20 minutes. Scan results affected clinical decision making in 26 cases. There were ten graft stenoses, 10 distal stenoses, 5 large arteriovenous fistulas (AFV), and one limb with a stenosis and AFV. Four other limbs had incompressible vessels and normal angiodynograms. There were no false positives. Twenty-eight graft revisions were performed in 24 patients. Seven stenoses detected by angiodynogram were not accompanied by changes in ABI. Cumulative patency of revised grafts were 61% at 3 years. The detection of graft or distal arterial stenoses by color flow changes is accurate and rapid. Scanning is recommended for all lower extremity bypass grafts. ABI alone is not sufficient. Scanning helps in planning the surgical incision and may obviate arteriography in selected cases.

Aged↗
PubMed2005

The clinical performance of CAD/CAM-generated composite inlays.

BACKGROUND: The authors conducted a study to evaluate the longitudinal clinical performance of a resin-based composite (Paradigm, 3M ESPE, St. Paul, Minn.) for computer-aided design/computer-aided manufacturing (CAD/CAM)-generated adhesive inlays. METHODS: The researchers used a CAD/CAM unit (CEREC 2, Sirona Dental Systems, Bensheim Germany) to fabricate 40 porcelain (Vita Mark II, Vita Zahnfabrik, Bad Säckingen, Germany) and 40 resin-based composite (Paradigm, 3M ESPE) inlays. Both restorative materials were cemented with a total-etch technique using Single Bond dental adhesive (3M ESPE) and a dual-cured resin cement (RelyX ARC Adhesive Resin Cement, 3M ESPE). Two examiners evaluated the inlays using modified U.S. Public Health Service (PHS) criteria at six months, one year, two years and three years. RESULTS: No sensitivity was reported for either material at any recall period. There was no significant difference between the two materials relative to margin adaptation at three years. Margin adaptation initially was very good for both materials, with an increase in margin detection due to apparent wear of the resin-based composite luting agent. There was a significant difference in color match between the two materials at three years, with 91.4 percent of the resin-based composite inlays and 58.8 percent of the porcelain inlays rated Alfa. CONCLUSIONS AND CLINICAL IMPLICATIONS: The resin-based composite inlays had a significantly better color match at three years than did the porcelain inlays. Resin-based composite CAD/CAM inlays performed as well as porcelain CAD/CAM inlays after three years of clinical service.

Bicuspid↗
PubMed2005

Color stability of dry earth pigmented maxillofacial silicone A-2186 subjected to microwave energy exposure.

PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. MATERIALS AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments.

Analysis of Variance↗
PubMed2003

Effect of resin surface sealers on improvement of stain resistance for a composite provisional material.

BACKGROUND: Resistance to staining is desirable to maintain the esthetic appearance of a provisional material. A resin sealant may improve stain resistance. PURPOSE: Color changes of a resin composite provisional material were measured by reflection spectrophotometry after storage in three staining solutions and water to determine stain resistance when treated with three methacrylate or urethane dimethacrylate resin surface sealants and when left untreated. MATERIALS AND METHODS: Specimens of a resin composite provisional material received one of three resin sealants (Fortify Plus, Bisco, Inc., Schaumburg, IL; Jet Seal, Lang Dental Manfacturing, Wheeling, IL; Triad LC, Dentsply International, York, PA, USA) or no surface sealer and then were stored for 72 hours in one of four staining solutions (water [control], black coffee, cranberry juice, red wine). Color was measured by CIE L*a*b* on a reflection spectrophotometer (Color-Eye 7000, Macbeth Division, Kollmorgen Instruments, Newburgh, NY, USA) at baseline and after storage. Color change (deltaE*) was calculated and analyzed statistically by two-factor analysis of variance, with four solutions and four surface treatments as independent variables. RESULTS: deltaE* ranged from 0.7 to 1.7 in water, from 1.1 to 5.5 in cranberry juice, from 1.1 to 6.5 in black coffee, and from 1.5 to 3.9 in red wine. Statistically significant differences were observed (p < .05), with Fortify Plus showing increased staining (deltaE* > 3.3) and Jet Seal and Triad LC showing decreased staining (deltaE* < 2.0) in cranberry juice and coffee compared with staining of the unsealed specimens. Only Jet Seal provided resistance to staining in red wine. CONCLUSIONS: Specimens without a surface sealer had statistically higher (p < .05) and perceptible or nearly perceptible color changes in cranberry juice, black coffee, and red wine than in water. Specimens coated with Jet Seal had statistically lower (p < .05) color changes than uncoated specimens in cranberry juice, black coffee, and red wine. When coated, the color changes of the stained specimens were not perceptible. Specimens coated with Triad LC had statistically lower (p < .05) color changes than unsealed specimens in cranberry juice and black coffee. When sealed, the color changes of the specimens stained with cranberry juice and black coffee were not perceptible. Both unsealed and sealed specimens stained with red wine were nearly perceptible. Specimens coated with Fortify Plus had statistically higher (p < .05) color changes than uncoated specimens in cranberry juice and black coffee but statistically the same (p < .05) color change as uncoated specimens in red wine. These specimens had perceptible color changes in cranberry juice, black coffee, and red wine. CLINICAL SIGNIFICANCE: Surface of methacrylate or dimethacrylate resins can improve resistance of a resin composite provisional material to staining caused by cranberry juice, black coffee, and red wine.

Acrylic Resins↗
PubMed2005

The color differences between different thicknesses of resin veneered over amalgam.

STATEMENT OF PROBLEM: Composites and compomers are popular in dental practice. However, little is known about their esthetic appearance as veneering restorative materials over amalgam restorations. PURPOSE: This in vitro study was designed to assess the color differences of composite and compomer restorative materials, placed in thicknesses of 1 mm and 2 mm over amalgam. MATERIAL AND METHODS: Thirty six cylindrical Teflon molds were filled with amalgam (13 mm diameter, 2 mm thickness) and stored at 37 degrees C and 100% relative humidity for 7 days. Nine veneers (for each thickness of 1 and 2 mm) were fabricated from four types of tooth-colored restorative material, Dyract AP (DYR), Compoglass F (COMP), Herculite XRV (XRV), and Vitalecense (VIT), over amalgam specimens using Teflon-split molds and following the manufacturers' instructions. A spectrophotometer was used to measure the color difference DeltaE* between the two thicknesses. RESULTS: Color difference DeltaE* values for 1 mm thickness veneers [XRV (2.52), Comp (5.46), VIT (6.73), and DYR (6.88)] were statistically significantly higher than the 2 mm thickness [XRV (1.32), Comp (3.24), VIT (4.89), and DYR (4.83)]. Although the XRV material had the lowest DeltaE* values, no statistically significant difference was found between the two thicknesses. The color measurements at L*, a*, and b* showed most materials became darker in color at either thickness. CONCLUSION: The thicker veneer specimens were found to be closer in color to the controls than the thinner specimens. Only XRV had color differences (DeltaE*) small enough to be considered clinically acceptable (2.52 and 1.32 at 1 mm and 2 mm, respectively). CLINICAL IMPLICATIONS: In this in vitro study the color of XRV was affected the least when veneered on amalgam. Opaquers may be needed to be used with thinner veneers to minimize the effect of amalgam background.

Analysis of Variance↗
PubMedDate not supplied

Polymerization color changes of esthetic restoratives.

The color changes of three different types of tooth-colored restoratives during polymerization were investigated using colorimetry. L*, a*, b* color parameters of five different shades of Z100 (a mini-filled composite resin), Fuji II LC (a resin-modified glass-ionomer cement), and Dyract (a polyacid-modified composite resin) were taken precure and postcure. The results showed that the restoratives evaluated all underwent color changes during polymerization. The polymerization changes in color parameters were shade and not material dependent. Changes in L* parameter or lightness during polymerization were significant for all material and shade combinations and had the greatest influence on the overall polymerization color change. As the color change was perceivable by the human eye for most shades of materials, the clinical practice of polymerizing some material on, or adjacent to, the undried tooth to confirm shades of esthetic restoratives before restorative procedures is prudent.

Colorimetry↗
PubMedDate not supplied

A longitudinal clinical study of Procera ceramic-veneered titanium copings.

PURPOSE: The purpose of the present paper was to study the long-term clinical results with ceramic-veneered Procera titanium copings. MATERIALS AND METHODS: A total of 44 titanium copings (fabricated for 22 patients) veneered with a low-fusing ceramic were followed for 60 to 78 months. The clinical examinations were performed by licensed specialists in prosthetic dentistry. The crowns were rated according to the California Dental Association system. In addition, Bleeding Index and Margin Index were also evaluated. RESULTS: In 3 crowns ceramic fractures necessitated their replacement. Two crowns had to be replaced because of caries. The ratings for surface and color had changed markedly, from excellent to acceptable. Regarding anatomic form, with the exception of the 3 fractured ceramic crowns, there were no obvious changes. The margin integrity, aside from the 2 crowned teeth with caries, was recorded as satisfactory (excellent or acceptable) for all other crowns; in fact, a large majority were rated excellent. Regarding Bleeding Index, there were no differences between crowned teeth and control teeth. Changes in Margin Index showed that the gingiva of the crowned teeth had retracted. CONCLUSION: Of the various clinical factors evaluated, only surface and color-related to the low-fusing ceramic used for veneering-showed any obvious change during the follow-up period. Otherwise the veneered titanium copings had, in general, performed well.

Adult↗
PubMed1999

In vivo comparison of a microfilled and a hybrid minifilled composite resin in Class III restorations: 2-year follow-up.

An in vivo comparison was made of two different types of restorative resins over a 2-year period: a microfilled resin (-1158262462Silux Plus, 3M-1158262462, USA) and a hybrid minifilled composite resin (-1158262461Herculite XRV, Kerr-1158262461, USA); 56 restorations were placed in 28 patients by one experienced dentist and examined by two independent evaluators using the United States Public Health Service (UPSHS) rating system for marginal adaptation, marginal discoloration, surface roughness, anatomic form and modified criteria for color match (direct and indirect evaluation). Modified criteria divided the classic A score into A1 for "not detectable" filling and A2 for "slightly discernible filling". Restorations were evaluated at baseline, 1 week, 6 months, 1 year and 2 years later. After 2 years, all materials were considered satisfactory for marginal adaptation, anatomic form and surface roughness (no "Charlie", or "Delta" ratings). No recurrent caries was observed. Clinical evaluation showed a significantly higher rate of marginal discoloration for the microfilled composite resin than the other resin. Hybrid composite resin materials may be expected to perform well as an anterior restorative material. Photographic ratings confirmed the clinical evaluation. The modified evaluation for color match demonstrated differences, which are not discernible with the USPHS system and showed, more rapidly, differences that appear later with the USPHS system.

Adolescent↗
PubMed1997

Clinical evaluation of hybrid ionomer restoratives in Class V abrasion lesions: two-year results.

Eighty Class V abrasion cavities were selected, and 20 cavities were restored with one of three resin-modified glass-ionomer materials (Fuji II LC, Photac-Fil, and Vitremer) or a polyacid-modified resin composite (Dyract). The restorations were clinically evaluated after 1 and 2 years with the US Public Health Service criteria. The results revealed a statistically significant difference in the percentage of restorations rated Alfa for color match at 2 years. No statistically significant difference was found in the percentage of alfa rating for anatomic form. Restorations of all materials showed some marginal discrepancies that were not statistically significant.

Compomers↗
PubMed1994

Techniques for aesthetic enhancement of porcelain laminate veneer restorations: a case report.

The article is a clinical report of various techniques to enhance the aesthetic outcome of porcelain veneer restorations. Color and contour evaluation, increase in shade value, bleaching, and the use of temporary veneer restorations are presented and discussed. A case is used to illustrate the procedures. The learning objective of this article is to expand and update the knowledge of variations in current porcelain veneer restoration techniques.

Adult↗
PubMed2003

Clinical evaluation of a new resilient denture liner. Part 1: Compliance and color evaluation.

PURPOSE: A new experimental resilient denture liner (MPDS-SL; Lai Laboratories, Burnsville, MN) and Molloplast-B (Buffalo Dental Manufacturing, Syosset, NY) were clinically evaluated for compliance and color change over a 1-year period. MATERIALS AND METHODS: In this crossover study, each of 20 patients had 2 dentures fabricated with long-term, silicone-based resilient liners, 1 denture with Molloplast-B and the other with MPDS-SL. Each denture was used for 6 months, during which time each patient kept a journal detailing his or her use and cleaning regimen. The 2 materials were assessed for compliance and color at the beginning of the study and again after 3 months and 6 months of use. Compliance was determined by applying a 3-lb force to the surface of the material following a square-wave pattern, using a closed-loop servohydraulic testing system. The force and position values were recorded using a storage oscilloscope. Compliance was measured at 3 locations on each denture and analyzed using data-acquisition software. Images of the dentures were captured using a zoom stereomicroscope with a charge-coupled video camera and image analysis software. The color was measured at 3 locations on each denture; RGB and L* a* b* were calculated. RESULTS: Compliance increased from baseline to 3 months and from 3 months to 6 months for almost all locations on both materials. Molloplast-B and MPDS-SL differed in average change in compliance at 6 months; the average change in compliance from baseline to 6 months was 453 (standard error, 46) for Molloplast-B and 284 (standard error, 46) for MPDS-SL (p = 0.019). For both materials, color changed significantly from baseline to 3 months and from baseline to 6 months (p < 0.01). MPDS-SL changed significantly less than Molloplast-B from baseline to 6 months for R (p = 0.039), G (p = 0.037), B (p = 0.005), and L* (p = 0.042). CONCLUSION: For both materials, compliance increased over 6 months of wear. The color change for MPDS-SL was considerably less significant than that for Molloplast-B.

Aged↗
PubMedDate not supplied

Color of restorative materials after staining and bleaching.

This study determined the effect of a 10% carbamide peroxide bleaching agent on the removal of stain from restorative materials. Color changes (delta E*) of three restorative materials [compomer (Dyract); composite (TPH Spectrum); hybrid ionomer (Fuji II LC)] when exposed to juice/tea, chlorhexidine (CH), and water (control) for 120 hours were studied. Stained specimens were treated for two 2-hour periods with a bleaching agent (Platinum Tooth Whitening System) with and without the active ingredient. Color was measured at baseline, after staining, and after treatment using the CIE L*a*b* color system relative to CIE standard illuminant A (incandescent light) as measured by a reflection spectrophotometer. Means and standard deviations (n = 5) were calculated and data were analyzed by four-way ANOVA. All variables and interactions were statistically significant. Color changes caused by CH and water were not perceptible (delta E* < 3.3). After two 2-hour treatments, the following occurred with specimens stained with cranberry juice/tea: paste with and without active ingredient perceptibly changed color of stained composite. The stained hybrid ionomer perceptibly changed color after treatment with paste containing active ingredient but did not change after exposure to paste without active ingredient. The stained compomer was not perceptibly different with either treatment. Platinum successfully removed stains from the composite and hybrid ionomer tested.

Analysis of Variance↗